PSV sizing calculator – fire case for liquid filled vessel

Pressure Safety valve sizing calculator for fire case for a liquid filled vessel. This calculators should be used when gas resulting from boiling of the liquid is discharged through the safety relief valve.

Vessel Diameter

m

Vessel Length (TL-TL)

m

Vessel height above ground

m

Liquid level in the vessel (HHLL-TL)

m

Vessel Orientation

Type of head

Area considered for calculation

Environmental Factor

Set pressure

barg

Accumulation

%

Type

Back pressure

barg

Coefficient of discharge Kd

(max=0.975)

Rupture disk upstream to PSV ?

Is released fluid steam ?

Relieving temperature

0C

Relieved Vapor Desnity

kg/m3

Isentropic coefficient (Cp/Cv)s

Moleculare weight

Compressibility factor (Z)

Latent heat of vaporization

kcal/kg

Relieving pressure

barg

Exposed area

m2

Minimum orifice area requirement

cm2

Gas flowrate to be relieved

kg/hr

The calculated area is the minimum orifice area required to allow the discharge of gas. The actual orifice area is the next higher available area. Following table presents the standard orifices with their designating letters and corresponding area.